Film straightener apparatus for wrapping articles in stretchable film

ABSTRACT

In apparatus for completing the wrapping of articles in heatsealable stretchable film, straightening rolls pull the laterally-extending portions of the tubular wrap film laterally and forwardly to remove all wrinkles and gatherings from the film just before the laterally extending portions are gripped by gripper means and pulled diagonally downwardly in a substantially vertical plane to stretch the film tightly about the article.

States Patent [1 1 [111 3,748,825

Chant, Jr. July 31, 1973 [5 FILM STRAIGHTENER APPARATUS FOR 3,537,23511/1970 Pepmeier et al 53/373 WRAPPING ARTICLES IN STRETCHABLE 3,621,63211/1971 Browning 53/138 A FILM Inventor: Albert H. Chant, Jr., Holland,Pa.

Assignee: J. B. Dove lnc., Levittown, Pa.

Filed: Apr. 22, 1971 Appl. No.: 136,358

Related U.S. Application Data Continuation-in-part of Ser. No, 823,736,May 12, 1969, Pat. No. 3,629,993.

U.S. Cl. 53/379, 53/206 Int. Cl..... B65b 7/08, B65b 51/10, B65b 65/00Field of Search 53/203, 206, 209,

References Cited UNITED STATES PATENT-S 1/1965 lrwin et al 53/14 PrimaryExaminerRobert C. Riordon Assistant Examiner-Neil Abrams Attorney-Paul &Paul [57] ABSTRACT In apparatus for completing the wrapping of articlesin heat-scalable stretchable film, straightening rolls pull thelaterally-extending portions of the tubular wrap film laterally andforwardly to remove all wrinkles and gatherings from the film justbefore the laterally extending portions are gripped by gripper means andpulled diagonally downwardly in a substantially vertical plane tostretch the film tightly about the article.

6 Claims, 5 Drawing Figures PATENIEU JUL3 I sum 1 or 3 INVEN'IOR.

Albert H. Chant, Jr.

ATTORNEYS.

PAIENIEU uw 1 I975 SHEU 2 [IF 3 INVENTOR Albert H.Ch0nr, Jr.

3 O 4 I 5 4 H ATTORNEYS PAIENIED JUL 3 SHEH 3 BF 3 mfw z ATTORNEYS.

FILM STRAIGHTENER APPARATUS FOR WRAPPING ARTICLES IN STRETCIIABLE FILMCROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of my copending earlier-filed patent applicationSer. No. 823,736, filed May 12, 1969, entitled Apparatus for WrappingArticles in Stretchable Film, now US. Pat. No. 3,629,993, issuedDecember 28, 1971. In the pres ent application, component parts whichare common to both the present application and my earlier applicationare identified by the same reference numerals.

FIELD OF THE INVENTION This invention relates to apparatus for wrappingarticles in stretchable heat-sealable film. One example of the sort ofarticle which may be wrapped by the apparatus of the present inventionis the well-known tray of meat or poultry as displayed for sale in therefrigerated display counter of a super-market.

BACKGROUND OF THE INVENTION In my earlier patent application, Ser. No.823,736, now US. Pat. No. 3,629,993, apparatus is disclosed for wrappingarticles in stretchable heat-sealable film wherein gripper chains oneach side of the conveyor grip the top and bottom portions of the filmwhich extends laterally from opposite sides of the partially wrappedarticle and pulls the film downwardly and forwardly in substantiallyverticle planes. The film is pulled, to each side of the article, over afilm-guiding ledge which is higher than the undersurface or bottom ofthe article, thereby causing the film which projects laterally from thebottom of the article to pass upwardly along the sides of the articleand over the sides of the film-guiding ledge before entering into thegripper chains. By such means, the pull on the film is distributedbetwben the film covering the top and the film covering the bottom ofthe article, with consequent stretching of the film across both the topand underside of the article.

SUMMARY OF THE INVENTION The object of the present invention is toprovide means, in apparatus of the general type referred to above, forassuring that the film is fully stretched by the gripper means, and notmerely straightened or partially stretched.

Stated another way, the object of the present invention is to providemeans for taking out all wrinkles and gatherings which the partiallywrapped film would otherwise have at the time it enters the grippermeans. If such straightening means is not provided, the gripper means inpulling the film diagonally downwardly will be unable to stretch thewrinkled film about the package to the full extent desired.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view of a fragment ofthe wrapping apparatus showing the straightening device of the presentinvention;

FIG. 2 is an elevational view looking along the lines 2-2 of FIG. 1toward one side of the apparatus from the center axis the machine;

FIG. 3 is an elevational front view of one side of the machine lookingalong the lines 3-3 of FIG. 2;

FIG. 4 is an elevational view, enlarged, looking along the lines 44 ofFIG. 3, showing the straightening device of the present invention;

FIG. 5 is a diagrammatic illustration showing how the straighteningdevice operates to straighten out the film just before it enters intothe grip of the gripper chains.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, the articles movefrom right to left in the direction indicated by the arrow. Thepartiallywrapped articles, identified as A in FIG. 3, are placedsuccessively, either by manual or mechanical means, on the supportrollers 10, at the input end of the machine, the right-hand end asviewed in FIG. 1. At the time the article is so placed, it is partiallyenclosed in a tube of heat-scalable stretchable plastic film F. One filmtype would be stretchable plastic film of polyvinylchloride copolymers,otherwise known as PVC. As is well known, these are tough, non-toxicfilms characterized by the tendency to want to stick or cling to itself.

The tubular piece of PVC or other stretchable plastic film F, in whichthe article A is partially enclosed at the time it is deposited on therollers 10 at the input end of the machine, extends or projectslaterally in both directions beyond each side of the article, and theseprojecting protions, which for convenience are identified in the drawingby the letters PF, are supported on side ledges 12. It should be pointedout that the apparatus is symmetrical about its longitudinal centeraxis, each side having similar and corresponding parts. Accordingly, itwill be necessary to describe but one side of the machine.

As seen in FIG. 3, the rollers 10 are supported in generally U-shapedbrackets 41, with the outer leg 41B of the bracket being higher than theinner leg. The increased height of the outer leg 41B serves an importantand useful purpose in that it functions as a package guide and alsoprovides a support which maintains the level of the laterally projectingfilm portion PF above the bottom of the article A. As a result, the filmF about the bottom of the partially-wrapped article A is raised by thebracket leg 418 up along the side of the article A, as indicated by thedot-and-dash lines in FIG. 3. During the initial portion of thetransport through the machine, the laterally projecting portions of filmPF rest on the ledge 12.

The articles A are transported forwardly, toward the left as viewed inFIGS. 1 and 2, by carrier arms 76 which are carried at spaced intervalson the powerdriven carrier chain 74. Two of the arms 76, one on eachside of the apparatus, push against the article A and transport itforwardly toward the stretch station at which are located gripper chainsI8 and 20. Such gripper chains are mounted at each side of the pathalong which the articles are being transported.

The gripper chains 18 and 20 grab the ends of the laterally projectingportions PF of the film F and pull it progressively downwardly in adiagonally forward direction in a plane which is normal, orsubstantially normal to the path of movement of the article A throughthe machine. The film ends are not pulled laterally by the gripperchains, either in the outward or inward direction. The pull is onlyvertically downwardly along a diagonally forward path. The film F on thetop of the article and also at the underside of the article is subjectto lateral pull in both directions, but this lateral pull is the resultof a vertically downwardly pull on the film ends by the gripper chains.

The manner in which the projecting portions PF of the film on each sideof the article A enter into the nip of, and are gripped by, the gripperchains 18 and 20 is fully discussed in my earlier filed copendingapplication Ser. No. 823,736, now U.S. Pat. No. 3,629,993, and need notbe described in detail in the present application.

While either or both of the gripper chains 18 and 20 may be powerdriven, in the particular machine illustrated and described in myaforesaid US. Pat. No. 3,629,993, only the lower gripper chain 26 ispower driven, with the upper chain being in close intimate interleavedengagement with and driven by the driven lower chain. The samearrangement is illustrated in the present application.

Shown in FIG. 3 is a representation of a drive motor 42 and one of theside frames 50 of the machine. Motor 42 drives an output shaft 41 onwhich is mounted a sprocket 43 about which is trained a drive chain 44.Chain 44 is trained over and drives a sprocket 52 which is mounted onand fixed to a shaft 51 supported for rotation in the side frame 50.

Also mounted on and keyed to shaft 51 is a sprocket 55 about which thelower gripper chain 20 is trained. Also supported on shaft 51, as by akeyed bearing member 167, is a laterally-movable intermediate frame 67.A bracket is mounted on frame 167 which supports a track or guide 82(see FIG. 2) about which the lower gripper chain 20 is trained.

Also mounted on and keyed to shaft 51 is a sprocket 73. Sprocket 73drives a carrier chain 74 which carries a plurality of pusher arms 76 atspaced-apart locations. The carrier chain 74 is trained about a rail 77,best seen in FiG. 2. Rail 77 extends the full length of the machine.

For the purpose of enabling the apparatus to wrap articles of differentwidth, provision is made for adjusting the effective width of themachine. For this purpose, shaft 51 is provided with a keyway 151 for asubstantial portion of its length, and the bearing member 167 and bothof the sprockets 55 and 73 are keyed into the elongated keyway 151 andare adapted to be moved axially along the shaft 51. Movement along theshaft 51 is accomplished by two adjusting rods, one of which, rod 65, isshown in FIG. 3. The other rod does not appear in the drawings of thepresent application, but the width adjusting means now being referred toare fully described in my copending application, Ser. No. 823,736. Itwill be sufficient for the purpose of the present application to saythat a width-adjusting motor drives a rod which drives a chain whichdrives a sprocket 64 shown in FIG. 3 and keyed to shaft 65. Adjustingrod 65 is externally threaded and carries an internally threaded bearingmember 66 to which the intermediate frame 67 is secured, as by bolts.The lower end of the intermediate frame 67 is supported on the driveshaft 51 by the keyed bearing member 167. As seen in FIG. 3, bearingmember 167 is held by a clip 168 against a shoulder of a sleeve 71.Sleeve 71 is connected to, or integral with, the hub of sprocket S andthe hub of sprocket 73.

It will be seen that when the adjusting rod 65 is driven, the internallythreaded bearing member 66 moves axially along the shaft, thereby movingthe intermediate frame 67 either inward or outward according to thedirection of rotation of the adjusting motor and adjusting rods. Whenthe intermediate frame 67 is moved, the bearing member 167 on shaft 51is moved axially along shaft 51 and so are sprockets 55 and 73 togetherwith the track of the lower gripper chain 20, and the track of the uppergripper chain 18. Also moved is rail 77 of the carrier chain 74, sincerail 77 is connected to the intermediate frame 67 by a support member78, a fragment of which is shown in FIG. 3.

As already indicated hereinabove, in the embodiment illustrated in myearlier-filed application, and also in the present application, only thelower gripper chain 20 is power driven. The upper chain 18 is lockedwith and is driven by the lower chain. In some cases it may be desirableto drive the upper instead of the lower gripper chain, and in othercases it may be desirable to drive both. In any event, the gripperchains are, of course, driven at a speed which is related to the speedat which the articles are being pushed through the machine by thecarrier arms 76. This is most readily achieved by driving both thecarrier chain 74 and the gripper chains from a common drive shaft,namely, shaft 51. It is important that the horizontal component of thegripper chain speed be equal to, or be somewhat greater than, the speedof the pusher or carrier arms 76, as otherwise package damage mayresult.

With respect now to the straightening device which is added as animprovement to the apparatus described in my earlier-filed application.It has been previously indicated hereinabove that one type ofheat-scalable stretchable plastic film which is popularly employed forpackage wrapping is PVC, a polyvinylchloride polymer, since this type offilm is tough and non-toxic. However, PVC has a tendency to cling toitself.

If the tubular wrapped film, in which the article A is partially wrappedat the time it is deposited on the rollers 10, is wrinkled or gatheredupon itself, then the gripper chains in pulling downwardly on the filmmay merely straighten out the film without any stretching, or maystraighten out the film with some degree of stretching but less thanfull stretching. To assure that the film is fully stretched by thegripper chains, a straightening device is, in accordance with thepresent invention, incorporated into the wrapping machine described andclaimed in my earlier filed copending application.

As seen in FIGS. 2 and 3, and as previously de scribed, the drive motor40 drives shaft 51 through drive chain 44 and sprocket 52. In accordancewith the present invention, sleeve 71 on shaft 51 is extended to theleft, as viewed in FIG. 3, beyond bearing member 167, anda gear ismounted on the extension 171 of sleeve 71. Gear 110 meshes with anddrives a gear 111 which is mounted on a stub shaft 168 supported in aplate 167 which is bolted to the intermediate frame 67. Mounted on andkeyed to the stub shaft 168 is a sprocket 112 about which is trained achain 113. The other end of chain 113 is trained about and drives asprocket l 14 mounted on and keyed to a stub shaft 170 which isjoumalled as by bearing 169 in the intermediate frame 67. Keyed to shaft170 and rotatable therewith is a pulley 115 having trained thereabout apulley belt 1 16, best seen in FIG. 5. As seen in FIG. 4, belt 1 16 istrained over a guide pulley 117, under guide pulley 1 18, about the workpulley 119, and over a guide pulley 120. The pulleys 117, 118, 119 and1120 are mounted on a mounting plate which is secured, as by screws,

to the intermediate frame 67. The major portion 131 of mounting plate130 lies in a plane parallel to that of the intermediate frame 67, butthe lower corner portion 132 is angularly disposed relative to the plateof the intermediate frame 67. Guide pulleys 117 and 120 are mounted onthe portion 131, but guide pulley 118 and work pulley 119 are mounted onthe angularly disposed portion 132.

A slot is cut in ledge 12 just below work pulley 119 and a spring-biasedroller 121 is mounted on the undersurface of ledge 12 to exert upwardpressure against the belt 116 at pulley 119. The roller 121 is soangularly mounted that it rotates in the same angular plane as that ofthe pulleys 119 and 118. The gear ratio between gears 110 and 111 is sochosen that belt 116 is pulled about work roller 119 at a surface speedsomewhat greater than that at which the carrier arms 76 are moving thepackage A forwardly. As a result, and due to the angular disposition ofthe roller 119 and its springbiased backup roller 121, thelaterally-extending film PF is pulled both laterally and forwardly. Thisaction occurs at both sides of the machine, and accordingly, anywrinkles or gatherings of the film are straightened out just before thefilm ends enter into the grip of the gripper chains 18 and 20. Thus, thegripper chains 18 and 20 are able to perform their intended purpose offully stretching the film about the article.

Work pulley 119 and spring-biased pre-load wheel 121 may preferably bedisposed at an angle of the order of 30 relative to the center axis ofthe machine or path of movement of the articles A. The angle is notcritical and may vary to either side of 30 by some 5 to It is important,however, that the work pulley 119 and belt 116 exert both a forward andlateral pull on the film ends.

It is desirable that the belt 116 have a surface speed, at its point ofcontact with the film, equal to or greater than that of the gripper orstretch chains 18, 20. This speed, as previously indicated, should befaster than the speed at which the pushers 76 push the article A throughthe machine. The relationships as to speed are most readily achieved byusing a common drive for the stretch chains, straightener, and articlepushers. By such an arrangement, a forward pull may be provided on thearticle which relieves the pressure of the pushers and avoids possibledamage to the package from excessive push force.

The belt 116 in the straightener device may be round or V-shaped incross section. It is made of frictional material, preferablypolyurethane.

in the illustrated machine, the work pulley 119 is located above thefilm, and the pre-load wheel 121 is below the film. These positions may,however, be reversed.

The straightener device has been illustrated in combination with astretch wrapping machine in which the lower one of the stretch chains 18and is power driven. The straightener device may, however, also beincorporated into a stretch wrap machine in which the upper one of thestretch chains is driven. Or, the straightener device may be usedindependently of the stretch mechanism.

What is claimed is:

1. Apparatus for wrapping articles in stretchable film, said apparatusincluding:

a. support means for supporting a series of articles partially wrappedin tubular manner with stretchable film the open ends of which projectlaterally in both directions beyond opposite sides of the articles;

b. carrier means for transporting said series of partially wrappedarticles in succession along said sup port means;

0. a film-stretching station;

(1. film-straightening means immediately preceeding said film stretchingstation for pulling said laterally projecting portions of filmdiagonally forwardly and laterally relative to the advancing article toremove lateral drag and laterally straighten out said dragging portionsjust before said projecting portions are presented to saidfilmstretching station;

c. said film-straightening means comprising a moving surface in contactwith said laterally projecting portions and having a surface speed atits point of contact with the film which is faster than the speed atwhich said articles are being transportedby said carrier means;

said film-stretching station including;

f-l. a pair of endless gripper chains disposed in vertical relation, oneabove the other, at each side of said support means;

f-2. track means for each of said gripper chains maintaining the upperreach of the lower chain in continuous interleaved interlocking pressureengagement with the lower reach of the upper chain;

f-3. means for driving said gripper chains at a speed relating to thatof said carrier means and such that the horizontal vector component ofthe gripper-chain speed is greater than the transport speed of thecarrier means;

f-4. said gripper chains operating to grip the ends of said projectingportions of said film and to pull the same diagonally downward below theadvancing article and forward thereof in substantially vertical planesto progressively stretch said film over said article.

2. Apparatus according to claim 1 characterized in that: a. film guidemeans are provided supported at the sides of said carrier means andforming at each side a ledge at a level higher than the undersurface ofthe articles transported by said carrier means for causing laterallyprojecting portions of said bottom portion of said film to pass upwardlyalong the sides of the transported articles and over said ledges of saidfilm guide means before entering into said gripper means to be pulleddiagonally downwardly and forwardly thereby, whereby the pull on saidstretchable filmis is distributed between the film covering the top andbottom of the article with consequent stretching of the film across boththe top and underside of said articles.

3. Apparatus according to claim 1 wherein:

a. said moving surface of said film-straightening means is an endlessbelt trained about a series of pulleys at least one of which is sopositioned that the portion of belt trained thereabout contacts saidlaterally projecting portions of said film;

b. said pulley, about which the film-contacting portion of said belt istrained, is disposed at such an angle relative to the center axis ofsaid machine that the film-contacting portion of belt pulls thelaterally projecting film substantially forwardly as well as laterally.

film-contacting belt is trained, is disposed at an angle of between 20and 40 relative to the center axis of the wrapping apparatus.

6. Apparatus according to claim 3 characterized in that said angularlydisposed pulley disposed at an angle of the order of 30 relative to thecenter axis of the wrapping apparatus.

1. Apparatus for wrapping articles in stretchable film, said apparatusincluding: a. support means for supporting a series of articlespartially wrapped in tubular manner with stretchable film the open endsof which project laterally in both directions beyond opposite sides ofthe articles; b. carrier means for transporting said series of partiallywrapped articles in succession along said support means; c. afilm-stretching station; d. film-straightening means immediatelypreceeding said filmstretching station for pulling said laterallyprojecting portions of film diagonally forwardly and laterally relativeto the advancing article to remove lateral drag and laterally straightenout said dragging portions just before said projecting portions arepresented to said filmstretching station; e. said film-straighteningmeans comprising a moving surface in contact with said laterallyprojecting portions and having a surface speed at its point of contactwith the film which is faster than the speed at which said articles arebeing transported by said carrier means; f. said film-stretching stationincluding; f-1. a pair of endless gripper chains disposed in verticalrelation, one above the other, at each side of said support means; f-2.track means for each of said gripper chains maintaining the upper reachof the lower chain in continuous interleaved interlocking pressureengagement with the lower reach of the upper chain; f-3. means fordriving said gripper chains at a speed relating to that of said carriermeans and such that the horizontal vector component of the gripper-chainspeed is greater than the transport speed of the carrier means; f-4.said gripper chains operating to grip the ends of said projectingportions of said film and to pull the same diagonally downward below theadvancing article and forward thereof in substantially vertical planesto progressively stretch said film over said article.
 2. Apparatusaccording to claim 1 characterized in that: a. film guide means areprovided supported at the sides of said carrier means and forming ateach side a ledge at a level higher than the undersurface of thearticles transported by saiD carrier means for causing laterallyprojecting portions of said bottom portion of said film to pass upwardlyalong the sides of the transported articles and over said ledges of saidfilm guide means before entering into said gripper means to be pulleddiagonally downwardly and forwardly thereby, whereby the pull on saidstretchable filmis is distributed between the film covering the top andbottom of the article with consequent stretching of the film across boththe top and underside of said articles.
 3. Apparatus according to claim1 wherein: a. said moving surface of said film-straightening means is anendless belt trained about a series of pulleys at least one of which isso positioned that the portion of belt trained thereabout contacts saidlaterally projecting portions of said film; b. said pulley, about whichthe film-contacting portion of said belt is trained, is disposed at suchan angle relative to the center axis of said machine that thefilm-contacting portion of belt pulls the laterally projecting filmsubstantially forwardly as well as laterally.
 4. Apparatus according toclaim 3 characterized in that a spring biased back-up roller is provideddisposed in the same plane as said angularly disposed pulley forengaging the laterally-projecting portion of film on the oppositesurface of said film from said belt as it passes about said angularlydisposed pulley.
 5. Apparatus according to claim 3 characterized in thatsaid angularly disposed pulley, about which the film-contacting belt istrained, is disposed at an angle of between 20* and 40* relative to thecenter axis of the wrapping apparatus.
 6. Apparatus according to claim 3characterized in that said angularly disposed pulley disposed at anangle of the order of 30* relative to the center axis of the wrappingapparatus.